Leaky Joints - Compressed Air
#1
03-02-16, 11:56 AM
Leaky Joints - Compressed Air
I installed some 1/2" rigid metal pipe a couple years ago to run compressed air to my work shop and up to my driveway. I initially used paste to seal all the joints but several of the joints leaked at higher pressures (80 PSI+), so I disassembled everything and used Loctite 542. However, I still have leaks at several of the joints, and the pipes are as tight as I can get them. What's the deal? Should I not use any sealant at all? Is there some type of sealant I can apply without removing all of the joints (big PITA)?
#4
03-02-16, 12:44 PM
Group Moderator
If they are steel pipe I have have run into some that just would not seal. I blame it on cheap imports and the manufacturers taps and dies were worn out since no amount of tightening could get them to seal. 542 is recommended for fine threads so it's not really intended for coarse NPT threads but I don't know what else you could try. I'd consider getting new pipe or fittings.
#5
03-02-16, 12:48 PM
I'm not positive I used 542. It may have been another version of Loctite. I remember researching a couple different types and 542 was listed for all types of pipe up to 2" in diameter if I remember correctly. I'll check tonight when I get home. Regardless, I ordered a stick of Loctite 561 PST and will give that a try before resorting to more drastic measures. If that doesn't work, then I'll consider replacing the piping with 1/2" aluminum. McMaster has pipe rated to 150 psi, which is plenty enough for my system. A little pricey though, but I only need about 12 feet of pipe and six fittings.
#6
03-02-16, 03:17 PM
Join Date: Mar 2006
Location: Wet side of Washington state.
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Likely Pilot is correct and it is because of poor quality threads. Unfortunately, at this point you have likely stretched the fittings (internal threads) as well and nothing will cause it to seal.
I would use new fittings and this time use Permatex Number 1 joint compound. Permatex Number 1 is a hard setting compound so make sure you have the arrangement correct when you do it.
Gasket Sealants : Permatex® Form-A-Gasket® No. 1 Sealant
I would use new fittings and this time use Permatex Number 1 joint compound. Permatex Number 1 is a hard setting compound so make sure you have the arrangement correct when you do it.
Gasket Sealants : Permatex® Form-A-Gasket® No. 1 Sealant
#8
03-03-16, 11:43 AM
When you dry fit the fittings how many turns are you getting. Should be able to go 3 revolutions by hand. I have never had any problem with threaded pipe. We dont use galv. for comp air. we use carbon steel.
#9
02-22-18, 08:55 AM
Only going that far wouldn't copper with flared fittings work better?
#11
02-22-18, 04:50 PM
Member
Only going that far wouldn't copper with flared fittings work better?
Just use copper and soldered fittings, works great!
